To remove the exif data you need to call Imagick::stripImage() on the populated Imagick object and then call Imagick::writeImage() to save your changes.
How to strip exif data using Imagick - James Morris - JMOZ
» If you need to resize an image, you can also use Imagick::resizeThumbnail to strip the exif data in one call!
Source: blog.jmoz.co.uk
